A method is known that comprises layer hydraulic fracturing to improve productivity of wells and to increase its debit or intake capacity while watering the oil layers. Herein a single crack that is long enough is created within individual uniform layers to carry out a single or a multiple fracturing of the layer. At multi-layer accumulations, consisting of layers suit that has a weak hydrodynamic interconnection in between, an intervallic hydraulic fracturing of layers (directed hydraulic fracturing) is to be carried out. Operational liquid to be used for hydraulic fracturing of a layer is pumped into the layer via the tubing production string with a packer at the end to be further separated into the three kinds: the fracturing liquid, the sand carrier liquid, and the displacement fluid. (Suchkov B. M. Intensifying Oil Wells Output—Moscow—lzhevsk: Scientific Research Center “Regular and chaotic dynamics”; Computer research institute, 2007, pp. 396-410). Shutoff valves on well mouths and operational column are replaced with a special head for the hydraulic fracturing. As an operational liquid, there may be used technical layer water, salt and acid solutions (for carbonate basins), crude oil, etc. To decrease pressure losses (to 75%) high molecular weight polymers are added therein. To keep them open, the opened cracks besides the operational liquid are filled with some propping material, like glass sand, glass and metal balls and other mechanical materials sized 0.5 -1.5 mm. With the intervallic hydraulic fracturing at each particular layer of a suit comprising many layers those operations are carried out in conjunction with the processed interval isolation via the packer, sand and clay plug and special high-density liquids. The operational liquid pumping pressure exceeds ground pressure and overcomes strength properties of the layer processed.
The following describes main disadvantages of such a method of a force impact upon layers. High expenses in materials and power, and substantial time to be consumed, are needed to prepare the work that includes dismounting of the production well permanent equipment to install the replacing equipment to carry out the hydraulic fracturing. The industrial implementation must be preceded by technical and economic feasibility study for the method. Upon hydraulic fracturing completion, wells are to be deployed and shaken via regular methods for treating near-mine zones, thus requiring additional expenses and time to be consumed. A hydraulic fracturing crack relatively quickly is compressed by the ground pressure, despite the propping material therein. It is impossible to determine the crack fracturing formation direction together with its spatial location configuration within a layer, thus resulting in unexpected water and gas breaking into the wells. This method is quite sophisticated and it does not allow simultaneous treatment of even smaller area fields, as well as an entire field, thus remaining suitable only for individual wells.
A method is also known for electro-dynamic cleaning of a near-well zone off contaminants (Suchkov B. M. Intensifying Oil Wells Output—Moscow—lzhevsk: Scientific Research Center “Regular and chaotic dynamics,” Computer research institute, 2007, pp. 282-283), based upon simultaneous impact upon the near-well layer zone via raised depression and high-intensity direct-current electric field. At the contaminated near-well zone, it results in hydraulic fracturing of capillary sheaths within fine-pored slice due to electro-osmotic effect, thus resulting in appearance of electrochemical, electro-kinetic, thermal and other factors within the capillary environment. Depending on the sign of an electric charge at the well electrode, an acid or an alkaline environment is to be formed, the temperature would rise for 10-20degrees Celsius, superficial inter-phase tension is decreased, volume flow rate for fluid displacement towards the well would increase. This provides for the oil industrial income to be initiated from the production layer via influencing it simultaneously with decreasing pressure and the direct current electric field with varying polarity. The electrode is first is charged with negative charge to call for the clay mud infiltrate from the near-well zone. Later on, when hydrocarbons appear, their income is intensified via substituting the electrode charge sign with a positive one.
The disadvantages of this method include limited scope of use, lower efficiency, higher implementation cost and lower maintainability.
A method is further known for developing and increasing oil, gas and other mineral resources rate of extraction from the earth interior (RU 2102587) that is designated as a prototype. According to the prototype, wells are sealed with packers on the layer cap level and solid electrodes are preliminarily placed therein, with high-voltage alternating current put therethrough to initiate an electric arc while melting a fuse link between pairs of solid electrodes or electrodes contacts separation, or by discharging through the intervals between solid electrodes of two neighbor wells under electrical voltage increased therein. An electric arc is to strike through the most conductive slice within the layer that has sufficient natural electric conductance, arising during oil and gas field formation, between solid electrodes of two neighbor wells by preheating natural conductive slice of layer with subsequent discharge of intervals through the same layer slice. Then, in order to move electric arcs within in-situ space in necessary order and sequence, the striking voltages are applied to electrodes of new neighbor wells at the field and those wells where arcs had already burned are de-energized.
The method has a number of disadvantages. First, is low reliability of discharge and initiating the electric arc under the most conductive natural slice to be found within the layer, as its conductivity may change on different sites of the field due to rock property change therein as well as their permeability and fracturing, as well as due to composition change in layer waters, gases, oils and other factors that affect the conductivity. Another disadvantage is providing reliable contacts with natural conductive slices of layers while using solid electrodes with small areas of contacts with conductive slices in layers, may be complicated. Yet another disadvantage is high cost of method implementation due to necessity of substantial power consumption and creating high voltages to heat and discharge natural conductive slices in oil and gas layers and initiating electric arcs between neighbor wells resulting from non-uniformity and non-constancy of natural conductive slices conductivity and small area of solid electrodes contacts with them.